The overall objective of this research program continues to be the development of stereoselective syntheses and the stereochemical investigation of pathways leading to novel heterocyclic systems via small ring compounds. Since many heterocyclic structure are useful as alkylating agents in cancer chemotherapy, such knowledge is essential to the understanding of their mode of action at the molecular level. In addition, we intend to exploit intramolecular dipolar cycloaddition reactions as a method for obtaining functionalized organic compounds and structures of diverse architecture. Among the reactions to be studied are 1,1-cycloadditons of nitrile ylides and nitrilimines and 1,3-dipolar cycloadditions of diazo compounds and azides. A study of the basic chemistry of small ring heterocyclic compounds and of conformational and electronic factors in dipolar cycloadditions should provide important information that will enhance our understanding of the action of such chemicals in living systems. Many of the substances to be synthesized are expected to show interesting malignant-growth inhibiting properties and will be tested at the National Cancer Chemotherapy Service Center.